A bad Christian might be a person who says that they are a Christian but does not behave in a way that a Christian is supposed to behave. Given that there is no specific standard of behavior that atheists universally aspire to, is there any sense in which someone could be said to be a bad atheist?

Certainly.

It might be said that someone whose reason for atheism is grossly unsound is a bad atheist. For example, let’s say that a woman in a small community has attended church all her life. Over the years, she becomes fed up with the gossiping, hypocrisy, and petty bickering among churchgoers around town and decides she’s had enough: she quits the church and declares herself an atheist.

But the fact that Christians bicker has nothing to do with whether or not God exists. And even if this proved that Christianity is lacking in some way, it does not prove that no other religion has its metaphysics right. Rejecting one church because its members are bad Christians is not well-grounded atheism.

An immoral person who is also an atheist could be said to be a bad atheist. Such a person is a terrible example whose behavior makes life a little more difficult for morally responsible atheists because it perpetuates stereotypes. If the atheist brags about not having to be responsible because there is no divine retribution, it’s that much worse.

A minor type of bad atheist is the atheist who just isn’t that good at being an atheist. This is a person who makes sincere but misinformed arguments against religion or performs little acts of anti-religious protest (like teasing a relative who is praying before a meal) because it seems like that’s the sort of thing an atheist should do. Fortunately, these problems are nothing that a little education and life experience can’t take care of.

Far more worrisome is the abusive atheist. This is the dogmatic atheist who argues with venom instead of reason and declares anyone with religious belief “stupid.” Such people are as closed minded as the worst religious fundamentalist and do nothing to help advance the cause of free, intelligent thought.

Finally, there are those who are atheists in the same sense that some who only occasionally eats beef is a a vegetarian. This includes people who say they are atheists when they mean that they do not believe in the Judeo-Christian God, or who do not see the inherent conflict between atheism and certain kinds of spirituality or new-age nature worship. If you believe that nature created itself and has intelligence and goals, then you are not an atheist.